Compression Test 2001 XR650

Anyone know what a good compression test reading would be for a 2001 650.

Due dilegence on a used bike with well maintained bike with a few hours on it.

I found a site that said a minimum of 100psi. How does the compression ratio 10:1 vs 11:1 translate into fresh psi? Any insight appreciated.

R or L?....sounds like an R....

Anyone know what a good compression test reading would be for a 2001 650.

Due dilegence on a used bike with well maintained bike with a few hours on it.

I found a site that said a minimum of 100psi. How does the compression ratio 10:1 vs 11:1 translate into fresh psi? Any insight appreciated.

The problem is the decompresser. It keeps an exhaust valve open, so you don't see full compression.

Its a 650R.

I asked the local Honda dealer and the mechanic said a fresh rebuild would give 86 psi with decompressor engaged and 160 psi with decompressor lever released. So my next query is whats the cutoff pressure to be concerned, 120? 140?

Its a 650R.

I asked the local Honda dealer and the mechanic said a fresh rebuild would give 86 psi with decompressor engaged and 160 psi with decompressor lever released. So my next query is whats the cutoff pressure to be concerned, 120? 140?

I always thought that with the kick starter, you couldn't turn if fast enough to disengage the cam decompression system.

What are you measuring?

I havent tested it yet, I'll be test riding the bike and compression testing this weekend.

You may be right, I dont know that much about how the decompression system works, I presumed that if you dont - pull and hold - the decompression lever than you would be kicking against full compression, which is consistent with the 2 different PSI's noted from the honda dealer.

Guess I'll have to check it and find out.

cleonard,

do you know for sure if the 01 XR650R has an auto-decompression system that disengages once the rpms get high enough?

After reading a few other related posts, I started learn what you were referring to. The 160 psi the dealer mechanic gave me may be when the auto-decompressor is deactived somehow.

A motion pro leak down tester is a little spendy for my needs right now, I could put new valves in for the cost of one.

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